1. UCL Institute of Neurology, Queen Square; London UK
2. Department of Neurology; Ashford and St Peter's Hospital; Surrey UK
3. Parkinson's Disease and Movement Disorders Department; HYGEIA Hospital; Athens Greece
4. Neurology Clinic; Philipps University Marburg; Germany
5. Second Department of Neurology; University of Athens; Greece
6. Sobell Department of Motor Neurosciences and Movement Disorders, UCL, Institute of Neurology; UK